Ex parte XU et al.

Board of Patent Appeals and Interferences

Feb 25, 1998

08344509 (B.P.A.I. Feb. 25, 1998)

Application for patent filed November 23, 1994.1
1
THIS OPINION WAS NOT WRITTEN FOR PUBLICATION
The opinion in support of the decision being entered today (1) was not written
for publication in a law journal and (2) is not binding precedent of the Board.
Paper No. 13
UNITED STATES PATENT AND TRADEMARK OFFICE
_____________
BEFORE THE BOARD OF PATENT APPEALS
AND INTERFERENCES
_____________
Ex parte REN XU and KUEIR-WEEI CHOUR
_____________
Appeal No. 96-3649
Application 08/344,5091
______________
ON BRIEF
_______________
Before KIMLIN, JOHN D. SMITH and WEIFFENBACH, Administrative
Patent Judges.
JOHN D. SMITH, Administrative Patent Judge.
DECISION ON APPEAL
This is an appeal pursuant to 35 USC § 134 from the final
rejection of claims 1 through 29.
Claim 1 is representative and is reproduced below:
1. A method for the chemical vapor deposition of a
heterometaloxide film, comprising:
selecting a volatile precursor which contains
Appeal No. 96-3649
Application 08/344,509
Only an abstract of this publication is physically present in the2
record.
2
metal constituents in a stoichiometric ratio desired for said
film;
vaporizing said precursor at a selected rate;
hydrolyzing a portion of said precursor in the
vapor state to form a hydrolyzed precursor; and
reacting said hydrolyzed precursor on a substrate
to form a film containing said metal constituents in said
stoichiometric ratio.
The references of record relied upon by the examiner are:
Rothschild et al. (Rothschild) 4,888,203 Dec. 19, 1989
Purdy H1170 Apr. 6, 1993
Sladek et al. (Sladek), ?Low Temperature Metal Oxide Deposition
by Alkoxide Hydrolysis?, Journal article announcement No.
GRAI7301, published in Proceedings of the International
Conference on Chemical Vapor Deposition (3rd), Salt Lake City,
Utah, April 24-27, 1972, pages 215-231.2
Claims 1 through 6 and 23 through 29 stand rejected under 35
USC § 103 over Sladek in view of Purdy. Additionally, appealed
claims 7 through 22 stand similarly rejected under the same
section of the statute further in view of Rothschild.
We affirm.
The subject matter on appeal is directed to a method for the
chemical vapor deposition of a heterometaloxide film (e.g., a
Appeal No. 96-3649
Application 08/344,509
3
double metal oxide) comprising the steps of selecting and
vaporizing a volatile precursor (e.g., a double metal alkoxide)
which contains metal constituents in a stoichiometric ratio
desired for the ultimate deposited oxide film. Appellants’
method employs the step of hydrolyzing the volatile precursor in
the vapor state to form a hydrolyzed precursor followed by
reacting the hydrolyzed precursor on a substrate to form a film
containing the metal constituents in the desired stoichiometric
ratio, i.e., the stoichiometric ratio provided by the originally
selected volatile precursor.
In their ?Background of the Invention? section of the
specification at page 3, appellants indicate that metal oxide
chemical vapor deposition (MOCVD) of multicomponent oxide films
has successfully involved the use of separate metalorganic
compounds containing the respective film components as
precursors. As stated in this portion of the specification, the
precursor compounds are ordinarily independently transformed to
the vapor phase by evaporation or other means in a controlled
manner to achieve the desired molar ratio between vapor phase
species. This approach is said to inevitably require a trial-
and-error approach to achieve a precisely stoichiometric film
composition. At the top of page 7 of the specification,
Appeal No. 96-3649
Application 08/344,509
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appellants explain that when MOCVD is applied using double metal
alkoxide precursors, useful films are not produced. Appellants
explain that for all known double metal alkoxides, premature
decomposition producing individual metal oxides occurs at
temperatures much lower than the pyrolytic temperature of each
individual metal alkoxide. Thus standard chemical vapor
deposition pyrolysis reactions do not produce stoichiometric
oxide films because the M’ to M? ratio is lost prior to film
deposition. Appellants’ invention overcomes this problem by
using a vapor phase hydrolysis chemical vapor deposition
technique. Appellants contend that prior to their invention, it
was not known how to apply vapor deposition technology, notably
vapor phase hydrolysis, to double metal alkoxide precursors to
produce a film having the same stoichiometric ratio of metals as
exist in the precursor. See the specification at page 4, lines
16 through 19.
As evidence of obviousness of the claimed invention, the
examiner principally relies on Sladek and Purdy. Appellants
acknowledge (Brief, page 4) that although the combination
proposed (i.e., the use of a stoichiometric double metal alkoxide
precursor as described by Purdy in Sladek’s chemical vapor
deposition process) might be expected to produce an oxide film,
Appeal No. 96-3649
Application 08/344,509
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?it is not adduceable from the references that such a film would
be a stoichiometric oxide film.? Thus appellants contend that
neither reference contains any suggestion that a stoichiometric
double metal oxide film is achievable, much less how one would
produce such a film. More specifically, appellants contend that
Sladek is specifically directed to processes and products ?in
which stoichiometry is not a consideration.? We do not agree
this interpretation of Sladek, however.
Initially, we point out that our review of Sladek is
hampered because the examiner has provided only the abstract of
this multipage publication for review. Nevertheless, the Sladek
abstract indicates that films of a family of metal oxide
materials were produced by passing water and alkoxide vapors in
nitrogen over a substrate in an isothermal rectangular reactor.
More specifically, Sladek indicates that films of Al O , Nb O ,2 3 2 5
Sb O , TiO , and ZrO were obtained as amorphous films which were2 3 2 2
annealed at high temperatures to cause crystallization with
increases in the refractive index. Clearly, the above films are
stoichiometric films i.e, chemical compounds having definite
proportions of the respective elements. Moreover, that
stoichiometry is a consideration of importance to Sladek is
implied by Sladek’s teaching that films described as VO and BOx x
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Application 08/344,509
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(films having undefined stoichiometry) were not further tested.
We also do not agree with appellants’ argument that the
references provide no suggestion as to how to produce a
stoichiometric double metal oxide film. Admittedly, Sladek only
describes the successful formation of single metal oxide films by
using a vapor phase hydrolysis chemical vapor deposition
technique. Importantly, however, Sladek indicates that the films
were all obtained at low temperatures, i.e., from 25 to 130EC.
Remembering that the problem of using a known double metal
alkoxide in a standard MOCVD process is the premature thermal
decomposition of the alkoxide into the respective individual
metal alkoxide components because of the high temperature
conditions required for pyrolysis (specification, page 7), one of
ordinary skill in the art would have been led to utilize such a
double metal alkoxide precursor in the low temperature vapor
phase hydrolysis chemical vapor deposition technique of Sladek
with a reasonable expectation of producing a stoichiometric
double metal oxide film. Based on the above analysis, it is our
view that a prima facie case of obviousness has been established
for the subject matter defined by independent claim 1 and those
claims dependent thereon.
Appellants have asked for separate consideration of several
Appeal No. 96-3649
Application 08/344,509
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groups of claims as set forth in the Brief at page 3. With the
exception of appealed claim 12, we think that a prima facie case
of obviousness has been established for the subject matter
defined by these claims. Appealed claim 12, which is separately
argued, requires control of the substrate temperature to within
the range of about 400EC to about 800EC. Sladek’s disclosure
that a family of metal oxides CVD reactions were successfully
achieved using vapor phase hydrolysis chemical vapor deposition
techniques at temperatures from 25 to 130EC, in our view, is
insufficient to provide a reasonable expectation that at the
higher temperatures claimed, stoichiometric double metal oxide
films would have been achieved. Thus, we reverse the examiner’s
rejection as it applies to dependent claim 12.
With respect to independent method claim 7, appellants argue
that the prior art fails to suggest structure strategically
positioned, and arranged to promote a polycondensation reaction
of a hydrolyzed precursor on a substrate. Apparently, appellants
are referring to the claim language defining a structure
positioned within a reaction chamber ?in the proximity of said
reaction zone, said structure being constructed and arranged to
promote a polycondensation reaction of said hydrolyzed precursor
on the substrate?. Based on Figure 1 of the application, this
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Application 08/344,509
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claim language apparently refers to graphite susceptor 52.
However, Sladek’s teaching of the vapor phase hydrolysis of a
metal alkoxide by passing water and alkoxide vapors and nitrogen
over a substrate in a isothermal rectangular reactor at least
implies the presence of a substrate heating means structure for
carrying out a hydrolysis/condensation reaction necessary to
produce a stoichiometric family of metal oxide films.
Appellants contend that appealed claims 6, 7, 18, 23 and 29
distinguish over the prior art because they require an annealing
step which differs from the annealing procedure described in the
references. With respect to this argument, as the examiner has
clearly pointed out, Sladek teaches air annealing at 350 to
1000EC which causes crystallization of an amorphous film. How
appellants’ claimed annealing step differs from the prior art
annealing is not apparent. Thus, we think these claims are also
properly rejected. Likewise, although appellants argue that
appealed claims 18 and 23 require the formation of a ?perfect?
crystal structure, appellants have not addressed the disclosure
in Sladek that the air annealing step, which caused crystal-
lization, produced anything other than perfect crystalline films.
Finally, while appellants indicate that none of the references
Appeal No. 96-3649
Application 08/344,509
See Organic Chemistry, Morrison and Boyd, pages 370-375, 1959, copy3
attached.
9
suggests the vapor deposition of a stoichiometric hetero-
metaloxide film by subjecting a vaporized precursor to an ?SN2?
reaction as in appealed claims 24 through 29 (appellants
apparently refer to the reaction mechanism referred to as S 2 andN
known as substitution nucleophilic bimolecular mechanism) , it3
would appear that this mechanism would have been expected by a
person of ordinary skill in the art for the hydrolysis reaction
in question based on the structure of the known double metal
alkoxides. Compare the specification at page 5, lines 7 through
15.
In passing, we observe that the thrust of many of the
arguments in appellants’ Brief and indeed the disclosure in
appellants’ specification is that prior art workers have not
known how to apply vapor deposition technology, notably vapor
phase hydrolysis, to double alkoxide precursors to produce large
crystals containing the same stoichiometric ratio of metals that
exist in the precursor. In the event of any subsequent
prosecution of this application, the examiner may wish to
consider the propriety of a rejection of the appealed claims
under 35 USC § 112, first paragraph, ?enablement requirement?,
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Application 08/344,509
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particularly for the broadly drafted claims that are now present
in this appeal.
The examiner’s rejection of claim 12 is reversed. The
rejection of all other claims is affirmed. Accordingly, the
decision of the examiner is affirmed-in-part.
No time period for taking any subsequent action in
connection with this appeal may be extended under 37 CFR
§ 1.136(a).
AFFIRMED-IN-PART
)
EDWARD C. KIMLIN )
Administrative Patent Judge )
)
)
) BOARD OF PATENT
JOHN D. SMITH )
Administrative Patent Judge ) APPEALS AND
Appeal No. 96-3649
Application 08/344,509
11
)
) INTERFERENCES
)
CAMERON WEIFFENBACH )
Administrative Patent Judge )
David V. Trask
TRASK, BRITT and ROSSA
P.O. Box 2550
Salt Lake City, Utah 84110